Taliban militants overran Musa Qala in February, after British troops withdrew and handed over security responsibilities to local elders.

British military officials say the goal is to take back the town.

The Taliban says it has more than 2,000 armed fighters ready to defend Musa Qala.

Separately, NATO foreign ministers are discussing appointing an international "super" envoy to Afghanistan. The envoy would help better coordinate U.N. and NATO civilian and military efforts within the country.